1. Field of the Invention
The invention concerns a process for the filtration of thickened gluten with the addition of enzymes before or during filtration.
2. Discussion of the Background:
In the process of the production of corn starch the protein components of the corn, i.e., the gluten, have to be separated. This is done after the wet grinding of corn by a succession of steps for the removal of germ and fibrous matter and the centrifuging of the starch, whereby a fraction of gluten and mechanically damaged starch particles is obtained as the centrifuge product. This fraction is called thickened gluten. It is drained on drum filters, dried and used as protein-rich cattle feed.
The filtration of thickened gluten often presents problems. The water is tenaceously retained so that very little filtrate is obtained, the drying of which requires a large amount of heat energy. This problem is attributed to the swelling of the starch contained in the thickened gluten.
In U.S. Pat. No. 3,928,631, highly branched, partially insoluble polysaccharides are thought to be responsible for the filtration problems. By the addition of glucamylase to the thickened gluten at least one hour before the start cf filtration, the starch is decomposed to a large extent and the filtration properties considerably improved. However, the amylase treatment has the disadvantage that the starch which would have remained in the residue as a valuable feed component is lost in the form of dissolved dextrin and sugar. The filtrate is reused, in part, for the swelling of the corn. In this manner the amylase contained in the filtrate gets into the ground matter and affects the decomposition of starch, which causes another portion of it to be lost. A further part of the filtrate is thrown out and puts a burden on the wastewater treatment due to its content of starch decomposition products.